1. Field of the Invention
The present invention relates to a jumping device for exercise, and more particularly to a jumping device for exercise which includes an arc-shaped plate spring, a vertical member coupled at an upper end thereof to an upper end of the plate spring, a footrest coupled to a lower end of the vertical member while extending horizontally, and a shoe case mounted on the footrest while serving as a connecting rod adapted to maintain the shoe case in its horizontal state, thereby eliminating need for a separate connecting rod.
2. Description of the Related Art
Referring to FIG. 1a, a conventional jumping device is illustrated. As shown in FIG. 1a, the jumping device includes an arc-shaped plate spring 1, a vertical member 14 coupled at an upper end thereof to an upper end of the plate spring 1 by a coupling member 2, and a footrest 15 coupled to a lower end of the vertical member 14 while extending horizontally. A user's foot may be placed on the footrest 15. The jumping device also includes a hinge lever 10 hingably coupled at an upper end thereof to a desired portion of the footrest 15 by a roller 11, and a hoof lever 5 hingably coupled at an upper end thereof to a lower end of the hinge lever 10 by a roller 6 and fixedly mounted to the lower portion of the plate spring 1 in an overlapping state. The hoof lever 5 is provided at its lower end with a hoof 12 adapted to come into contact with the ground 13 during the use of the jumping device. The roller 6 comes into contact with one major surface of the plate spring 1. In order to support the plate spring 1 opposite to the roller 6, a support block 9 is mounted to the upper end of the hoof lever 5. In FIG. 1a, the reference numeral 4 denotes a set screw for coupling the lower end of the plate spring 1 to the lower end of the hoof lever 5. The reference numeral 26 denotes a cushion for absorbing impact generated during the use of the jumping device. Also, the reference numeral 16 denotes a connecting rod connected between the vertical member 14 and the footrest 15 and adapted to maintain the footrest 15 in perpendicular to the vertical member 14, that is, horizontally. The connection of the connecting rod 16 to the footrest 15 is achieved by a fixing pin 18. The reference numeral 3 denotes a guard for the heel of the user. The reference numeral 18′ denotes a knee holder fixedly mounted to the upper end of the vertical member 14 and adapted to hold the knee of the user. Where the user desires to use the jumping device, he first inserts his foot though the knee holder 18′ under the condition in which a shoe is worn on the foot, and lays the foot on the footrest 15, as shown in FIG. 1a. When the user presses the footrest 15, that is, applies a load to the footrest 15 via his foot, the plate spring 1 is bent by the load, thereby causing the footrest 15 to move downwardly. The downward movement of the footrest 15 is carried out until the hinge lever 10 comes into contact with the hoof lever 5, as shown in FIG. 1b. When the user raises his foot to release the load applied to the footrest 15, the resilience of the plate spring 1 is exerted on the footrest 15. As a result, the user can jump by virtue of the resilience of the plate spring 1. Thus, the jumping function of the jumping device is carried out. Where an excessive load is applied to the footrest 15, the angle defined between the footrest 15 and the vertical member 14 may widen, so that the footrest 15 no longer maintains its horizontal state. In order to prevent such a problem, the angle between the footrest 15 and the vertical member 14 is maintained by the connecting rod 16. However, the provision of the connecting rod 16 makes it difficult or impossible for persons having a large foot size to use the jumping device. Furthermore, a lot of time and skill are required to assemble the connecting rod 16 between the vertical member 14 and the footrest 15 while maintaining the footrest 15 in its horizontal state. In addition, it is difficult for persons having a thick calf to use the jumping device because the knee holder 18 has a ring shape. Due to such a ring shape of the knee holder 18, the time taken to put on the jumping device is increased.